1. Field of the Invention
The present invention relates to an insulator having a torque-resistant or torque-prevailing crimped insulator end fitting. More particularly, the invention is also directed to a method of crimping an insulator end fitting so as to be resistant to torque tending to loosen mounting bolt connections of the insulator.
The utilization of rubber-covered insulators possessing fiberglass cores, and which incorporate metal end fittings, is widely known and employed in connection with an extensive variety of both overhead and underground electrical power transmission devices. For instance, one such device employing an insulator comprises a pad mount switch gear wherein the insulator is utilized as a support mechanism for hardware which is at line potential, with such insulators being frequently in the configuration of so-called post insulators, as is known in the technology.
Ordinarily, in order to mount the insulator to the hardware, arranged at each end of the post insulator are between two or four bolts which are engage able into tapped or threaded bolt holes. Suitable lock washers are arranged on the bolts in order to eliminate any bolt rotation or loosening subsequent to the application of the appropriate necessary tightening torque to the connector bolts of the end fitting.
The prevention of any bolt loosening is imperative, inasmuch as any loose bolts can readily result in the insulator performing improperly, and could also be conceivably the cause of radio noise or static. In essence, an important problem facing the industry in connection with the foregoing resides in the prevention of any loosening of the connections of the end fittings, and resultingly, the attachment of the insulators to the devices where the insulators are employed as support mechanisms.
2. Discussion of the Prior Art
Presently, various types of end fittings for piping or similar uses are known and widely employed in industry and commerce.
Whittle, et al., U.S. Pat. No. 5,228,721 discloses a pipe fitting wherein a pipe end is adapted to be inserted into a suitable end fitting. The fitting has a tubular section insertable into the pipe end, and has a plurality of axially spaced, radially outwardly extending circumferential ribs. The pipe fitting, with the end of the pipe extending thereover, has the pipe end encompassed by an annular sleeve. A crimping ring is mounted on the sleeve and then crimped inwardly so as to cause the ribs to bite into and grippingly engage the inner circumferential wall surface of the pipe end, thereby locking all of the elements together. This is basically a standard type of crimping arrangement for various types of piping or the like, necessitating numerous components which are not particularly suitable for post insulators.
Anderson, U.S. Pat. Nos. 5,364,134 and 5,364,135 each disclose an end fitting for flexible conduits, wherein a crimping ring is adapted to be positioned about an axially a projecting portion of the end fitting so as to be insertable into the essentially cylindrical conduit. Thereafter, the crimping ring is crimped radially inwardly so as to provide a gripping and axially locked contact with the conduit and the end fitting.
Hayward, U.S. Pat. No. 4,797,121 discloses a "tee" fitting for tapping into a coaxial cable network, wherein crimping sleeves or rings are slid over an external insulation segment of the conduits and then crimped so as to produce a gripping or clamping engagement with the insulation and the fitting.
Although the foregoing publications disclose various types of crimping rings, none of these are applicable to providing the torque-resistant fastening of piping or conduits to end fittings for insulators of the type described herein, inasmuch as the various prior art crimping rings are not torque-prevailing or torque-resistant, and in effect, permit for rotational movement between the various fitting components while concurrently possessing only a limited degree of strength against the effects of axial tensile forces.